import React, {
    CSSProperties,
    useMemo,
    useState,
    useRef,
    useEffect,
} from 'react';
import styled, {  } from 'styled-components';
import { Icon } from '../icon';

const originPadding = 24; //原始间距

interface DragControlData {
    drag: boolean;
    x: number;
    itemkey: string;
}

interface DragHighlight {
    drag: boolean;
    itemkey: string;
}

interface TreeItemType {
    level: number;
    itemkey: string;
    highlight: DragHighlight;
    borderColor?: string;
}

type TreeGragType = {
    gkey: string,
    backColor?: string,
} & DragControlData;

const TreeGrag = styled.div<TreeGragType>`
    position: absolute;
    width: 100%;
    height: 90%;
    ${(props) => {
        switch (props.x) {
        case 1:
            return `margin-left:${-levelSpace}px ;`;
        case 2:
            return '';
        case 3:
            return `margin-left:${levelSpace}px  ;`;
        default:
            return '';
        }
    }};
    ${(props) => {
        if (props.itemkey === props.gkey) {
        return `background: ${props.backColor};`;
        }
    }}
`;

const TreeItem = styled.div<TreeItemType>`
    padding-left: ${(props) => originPadding * props.level}px;
    padding-top: 2px;
    padding-bottom: 2px;
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
    ${(props) => {
        if (props.highlight.drag && props.highlight.itemkey === props.itemkey) {
        return `border: 1px dashed ${props.borderColor};`;
        } else {
        return '';
        }
    }}
`;

const TreeIcon = styled.span<{ g: itemPropsRequired }>`
    & > svg {
        transition: linear 0.2s;
        height: 10px;
        margin-bottom: 5px;
        ${(props) => {
        if (props.g.children && props.g.children.length !== 0) {
        if (props.g.children[0] && props.g.children[0]['visible']) {
            return 'display:inline-block;transform: rotate(-90deg);';
        } else {
            return 'display:inline-block;';
        }
        } else {
        return 'opacity:0';
        }
    }};
    }
`;

const source = [
{
    value: '北京分行',
    children: [
    {
        value: '朝阳支行办事处',
        children: [
        { value: '朝阳支行办事处-1' },
        { value: '朝阳支行办事处-2' },
        ],
    },
    { value: '海淀支行办事处' },
    { value: '石景山支行办事处' },
    ],
},
{
    value: '天津分行',
    children: [
    { value: '和平支行办事处' },
    { value: '河东支行办事处' },
    { value: '南开支行办事处' },
    ],
},
];

const flatten = function (
    list: Array<itemProps>,
    level = 1,
    parent: itemProps,
    defaultExpand = true
): itemPropsRequired[] {
    let arr: itemPropsRequired[] = []; //收集所有子项
    list.forEach((item) => {
        item.level = level;
        if (item.expand === undefined) {
        item.expand = defaultExpand;
        }
        if (item.visible === undefined) {
        item.visible = true;
        }
        if (!parent.visible || !parent.expand) {
        item.visible = false;
        }
        if (item.key === undefined) {
        item.key = item.value + Math.random();
        }

        item.parent = parent;
        arr.push(item as itemPropsRequired);
        if (item['children']) {
        arr.push(...flatten(item['children'], level + 1, item, defaultExpand));
        }
    });
    return arr;
};

interface itemProps {
    value: string;
    level?: number;
    expand?: boolean;
    visible?: boolean;
    parent?: itemProps;
    children?: Array<itemProps>;
    key?: string;
}

interface itemPropsRequired
extends Omit<Required<itemProps>, 'children' | 'parent'> {
    children?: itemPropsRequired[];
    parent: itemPropsRequired;
}

const checkParent = function (g: itemPropsRequired) {
    return g.level === 1;
};

const levelSpace = 20; //同级生效间距
///1插上级 2插同级 3插下级 0不插
const switchInsert = function (diff: number, g: itemPropsRequired) {
    if (!isNaN(diff)) {
        const origin = g.level * 10; //目标原本padding
        if (diff < origin) {
        //移动到padding前全部算上级
        if (checkParent(g)) {
            //排除最顶级
            return 2;
        } else {
            return 1;
        }
        } else if (diff < origin + levelSpace) {
        return 2;
        } else {
        return 3;
        }
    } else {
        return 0;
    }
};

const findOrigin = function (key: string, data: itemPropsRequired[]) {
    const res = data.filter((v) => v.key === key);
    if (res.length > 0) {
        return res[0];
    } else {
        return null;
    }
};

const getParent = function (g: itemPropsRequired) {
    if (g.parent && g.parent.parent) {
        return g.parent.parent;
    } else {
        return g.parent;
    }
};

const judgeChildren = function (
    origin: itemPropsRequired,
    target: itemPropsRequired
) {
    let sign = true; //如果有孩子就是false
    const fn = (child: itemPropsRequired) => {
        if (child.children) {
        child.children.forEach((v) => {
            if (v === target) {
            sign = false;
            return;
            }
            fn(v);
        });
        }
    };
    fn(origin);
    return sign;
};

const changeOriginParent = function (origin: itemPropsRequired) {
    const parent = origin.parent;
    if (parent.children) {
        const index = parent.children.indexOf(origin);
        if (index > -1) {
        parent.children.splice(index, 1);
        }
        //下面这个方法会产生bug
        //parent.children = parent.children.filter((v) => v !== origin);
    }
};

const changeTargetParent = function (
    parent: itemPropsRequired,
    origin: itemPropsRequired,
    g: itemPropsRequired
) {
origin.parent = parent;
if (parent.children) {
    //判断应该插入父级节点哪里
    if (g.parent.children) {
    const index = g.parent.children.indexOf(g);
    if (index > -1) {
        parent.children.splice(index + 1, 0, origin);
    } else {
        //parent传递g会进来
        parent.children.push(origin);
    }
    } else {
    parent.children.push(origin);
    }
} else {
    parent.children = [origin];
}
};

const checkTargetOrigin = function (
    g: itemPropsRequired,
    origin: itemPropsRequired
) {
    return g !== origin;
};

const insertTop = function (
    key: string,
    g: itemPropsRequired,
    data: itemPropsRequired[],
    callback: Function
) {
    const origin = findOrigin(key, data);
    //origin插入target上级
    const parent = getParent(g);
    if (
        g.level !== 1 &&
        origin &&
        checkTargetOrigin(g, origin) &&
        judgeChildren(origin, g)
    ) {
        //修改以前父节点
        changeOriginParent(origin);
        //修改目标父节点的父节点（与父节点同级）
        changeTargetParent(parent, origin, g);
        callback();
    }
};

const insertMiddle = function (
    key: string,
    g: itemPropsRequired,
    data: itemPropsRequired[],
    callback: Function
) {
    const origin = findOrigin(key, data);
    //origin插入target同级
    const parent = g.parent;
    if (
        g.level !== 0 &&
        origin &&
        checkTargetOrigin(g, origin) &&
        judgeChildren(origin, g)
    ) {
        changeOriginParent(origin);
        changeTargetParent(parent, origin, g);
        callback();
    }
};

const insertLower = function (
    key: string,
    g: itemPropsRequired,
    data: itemPropsRequired[],
    callback: Function
) {
    const origin = findOrigin(key, data);
    const parent = g;
    if (origin && checkTargetOrigin(g, origin) && judgeChildren(origin, g)) {
        changeOriginParent(origin);
        changeTargetParent(parent, origin, g);
        callback();
    }
};

export function throttle(fn: Function, delay: number = 300) {
    let flag = true;
    return function (...args: any) {
        if (flag) {
        flag = false;
        fn(...args);
        setTimeout(() => {
            flag = true;
        }, delay);
        }
    };
}

export type TreeProps = {
    /** 数据源*/
    source: itemProps[];
    /** 是否可以拖拽 */
    drag?: boolean;
    /** 高亮边框颜色 */
    borderColor?: string;
    /** 拖拽提示色 */
    backColor?: string;
    /**外层样式*/
    style?: CSSProperties;
    /**外层类名*/
    classname?: string;
};

const changeVisible = (item: itemPropsRequired, callback: Function) => {
//给点击的children设置visible
    if (item.children) {
        //避免children有显示不一行为
        let visible: boolean;
        const depth = (item: itemPropsRequired[]) => {
        item.forEach((v) => {
            if (visible === undefined) {
            visible = !v.visible;
            }
            v.visible = visible;
            if (v.children) {
            //把孩子全部改掉
            depth(v.children);
            }
        });
        };
        depth(item.children);
        callback(); //改完后更新页面
    }   
};

export function Tree(props: TreeProps) {
const img = new Image();
img.src = 'https://www.easyicon.net/api/resizeApi.php?id=1200841&size=32';

const { backColor, borderColor, drag } = props;

const root = useMemo(() => {
    return {
    level: 0,
    visible: true,
    expand: true,
    children: source,
    value: 'root',
    };
}, [source]);
const [dragUpdate, setDragUpdate] = useState(0);
const data = useMemo(() => {
    return flatten(root.children, 1, root);
    // eslint-disable-next-line react-hooks/exhaustive-deps
}, [root, dragUpdate]);
const [start, setStart] = useState(0);
const forceUpdate = useState(0)[1];
const ref = useRef<HTMLDivElement>(null);

const [highlight, setHighlight] = useState({
    drag: true,
    itemkey: '',
});

useEffect(() => {
    if (ref.current) {
    setStart(ref.current.getBoundingClientRect().left); //为了找到起始
    }
}, []);

useEffect(() => {
    const handler = () => {
    setDragOver((prev) => ({ ...prev, drag: false }));
    setHighlight({
        drag: false,
        itemkey: '',
    });
    };
    window.addEventListener('dragend', handler);
    return () => {
    window.removeEventListener('dragend', handler);
    };
}, []);

const [dragOver, setDragOver] = useState<DragControlData>({
    drag: false,
    x: 0,
    itemkey: '',
});

const dragHandler = (
    clientX: number,
    itemkey: string,
    g: itemPropsRequired
) => {
    const diff = clientX - start;
    const x = switchInsert(diff, g);
    setDragOver({
    drag: true,
    x,
    itemkey,
    });
};

const callback = () => {
    forceUpdate((state) => state + 1);
};

const dragCallback = () => {
    setDragUpdate((state) => state + 1);
};

return (
    <div ref={ref}>
    {data
        .filter((v) => v.visible === true)
        .map((g) => {
        return (
            <TreeItem
            itemkey={g.key}
            highlight={highlight}
            level={g.level}
            borderColor={borderColor}
            draggable={drag}
            onClick={() => changeVisible(g, callback)}
            key={g.key}
            onDragStart={(e) => {
                e.dataTransfer.setData('atomkey', `${g.key}`);
                e.dataTransfer.setDragImage(img, 29, 29);
                setHighlight({
                drag: true,
                itemkey: g.key,
                });
            }}
            onDragOver={(e) => {
                e.preventDefault();
                throttle(dragHandler)(e.clientX, g.key, g);
            }}
            onDrop={(e) => {
                const key = e.dataTransfer.getData('atomkey');
                const left = e.clientX;
                const diff = left - start; //离顶部差值
                const res = switchInsert(diff, g);
                switch (res) {
                case 1:
                    insertTop(key, g, data, dragCallback);
                    break;
                case 2:
                    insertMiddle(key, g, data, dragCallback);
                    break;
                case 3:
                    insertLower(key, g, data, dragCallback);
                    break;
                default:
                    break;
                }
            }}
            >
            {dragOver.drag && (
                <TreeGrag
                gkey={g.key}
                backColor={backColor}
                drag={dragOver.drag}
                x={dragOver.x}
                itemkey={dragOver.itemkey}
                ></TreeGrag>
            )}
            <TreeIcon g={g}>
                <Icon icon="arrowdown"></Icon>
            </TreeIcon>
            <span>{g.value}</span>
            </TreeItem>
        );
        })}
    </div>
);
}
  
Tree.defaultProps = {
    source: [],
    drag: true,
    borderColor: '#53c94fa8',
    backColor: '#00000030',
};